Free space optical communications is a line-of-sight (LOS) technology that transmits a modulated beam of visible or infrared light through the atmosphere for broadband communications. In a manner similar to fiber optical communications, free space optical communication uses a modulated light emitting diode (LED), laser (light amplification by stimulated emission of radiation), or other light source for data transmission.
Various known beacon systems utilize modulated optical signals in conjunction with broadband high-speed detector devices. In these systems, the modulated optical signals are typically demodulated in electronics which include, for example, a mixer and a low-pass filter.
It would be useful to be able to provide a beacon system that utilizes modulated optical signals without requiring broadband or high-speed detector devices, or demodulation electronics. It would also be useful to be able to provide a silent alarm, indicator, beacon or the like that is visible only to select (i.e., enabled) viewers, sensors and/or detectors. It would also be useful to be able to be able to selectively enable the content that is viewable by particular viewers, sensors and/or detectors. It would also be useful to be able to provide an enhanced viewing experience in which select viewers of an image or sequence of images are provided with a mechanism that permits them to view supplemental image content that is not detectable by other viewers.